1. Field of the Invention
The present invention relates to a semiconductor manufacturing system. More particularly, the present invention relates to switching apparatus that opens and closes a valve disposed in a wafer-transfer passage located between chambers of the semiconductor manufacturing system.
2. Description of the Related Art
Most semiconductor manufacturing systems have a number of sealed chambers so that predetermined processes can be performed in a high vacuum ambient. The chambers include a plurality of process chambers for performing a predetermined process in a high vacuum state, a load-lock chamber for temporarily receiving a wafer before the wafer is transferred into one of the process chambers, and a transfer chamber used for transferring the wafer between the various chambers of the system. More specifically, the transfer chamber is connected to each of the load-lock and process chambers so that the wafer can be transferred between the load-lock chamber and one of the process chambers or between various ones of the process chambers.
A respective input/output valve (I/O valve) is interposed between the transfer chamber and each of the process chambers, and between the transfer chamber and the load-lock chamber.
Such a conventional I/O valve 12, and a switching apparatus 14 comprising an actuator 16 for opening and closing the valve 12, are illustrated in FIG. 1. In the conventional system, the I/O valve 12 cannot maintain a stable driving speed during operation because of a lack of control of the pressure and flow rate of fluid provided to the actuator 16 for driving the I/O valve 12. As a result, a vibration is set up in the system. The vibration of the system causes particles in the process chamber(s) to become unstable which, in turn, results in processing errors.
In view of the foregoing, the primary object of the invention is to provide an apparatus for smoothly driving an actuator of an input/output valve (I/O valve). Another object of the present invention is to provide a semiconductor manufacturing system which vibrates to a minimum extent when a wafer-transfer passage, that connects vacuum chambers thereof, is opened or closed.
The present invention is characterized by two fluid flow regulators that are disposed in series in an fluid line of the actuator of the I/O valve in order to regulate the flow rate of fluid into the actuator.
According to an aspect of the present invention, the fluid-driven actuator of the I/O valve has a close port and an open port, a first fluid line is connected to the close port, a second fluid line is connected to the open port, a first fluid flow regulator is disposed in each of the first and second fluid lines to regulate the flow rate of fluid, and a second fluid flow regulator is disposed in each of the first and second fluid lines to regulate the flow rate of the fluid that has passed the first fluid flow regulators.
In the preferred embodiment of the invention, each of the first and second fluid flow regulators may be a manually adjustable needle valve that allows the flow rate of the fluid to be regulated by hand. The actuator may be a double-acting pneumatic cylinder. In any case, the rate at which the I/O valve is driven is stabilized due to the fluid flow regulators. Thus, vibrations in the system are minimized to prevent particles from being shaken off into the atmosphere within a process chamber(s).